Power excavator



July 23, 1935 w. FERRIS POWER EXCAVATOR Filed Aug. 29, 1%1

5 Sheets-Sheet l I 71653 Fer/0's,

1N VEN TOR.

A TTORNEYS.

W. FERRIS POWER EXCAVATOR July 23, 1935.

Filed Aug. 29, 1951 3 Sheets-Sheet 2 7/6221? Frm's,

' INVENTOR.

y DCm,W W

- ATTORNEYS.

W. FERRIS July" 23, 1935.

3 Sheets-Sheet 5 d R. S .5 w W n V .b N N W m 1 m T 6 T. F A \w W Q? b 3% Y L \w A Q J .7 n Rh m w ww Q N 3 Kw M Q a R Q Q N Patented July 23, 19135 e U I ED STATES PATENT OFFICE acoaesu rowan EXCAVATOR Walter Ferris, .Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis., a corporation of Delaware Application August 29, 1931, Serial No. 560,077

1 1 Glaimso (Cl. 214-435) My invention relates to new and useful 1m" ically discontinuing or resuming the storage of provements in power excavators, loaders, and energ the like; and particularly to hydraulic drive 5315- The power shovel selected for illustration is terns therefor. of a well known type. It includes a truck frame 5 The present application is for an improvement ou ed p C p traction mechanism, over the invention de rib d i my copendjng conventionally indicated at H, and carrying a cir- Pat t 1,793,433 issued February 17, 1931 cular rack and track member l2, constituting the One object of the present invention is the prousu s pp t f r a v vi ra r platform vision of an eificient drive system, through which A pinion l4 fi d to a Vertical Shaft 10 the power derived from a, single prime v r naled in the platform l3, meshes with the mem- 10 may be advantageously applied to effect the s her 12 and coacts therewith to swing the platform eral motions characteristic of machines of the about a vertical axis in a well known manner. type mentioned, without sacrificing the fiexibil- The p m Carries t usual pp Supporting ity of operation and ease of control ordinarily boom 15 and the 1 9 d pp hillsil drum 15 found in steam driven machines of this type. controlled in the usual manner,. a d operated 15 A further object of this invention is to prothrough ppr pr r 8 nd 9, rom n vide means for relieving the prime mover of exctric motor, 20, used as prime mover. The ccssive peak loads, by hydraulically storing up traction mechanism is driven from the gear 19 energy during times of small direct load, to be through a conventional gear train 2i and shaft 20, used at times when there would otherwise be ex- 22 under control clutch The m cessive demands on the prime mover. y' c that Of hoisting the p is A more particular object of the present inventhus effected from the electric motor, tion is to supply a device for automatically dishrou h direct mechanical connections which do continuing the hydraulic storage of energy whenn t difi r mat r al y fr m sta dard p t a 25 ever a certain predetermined maximum of enneed not be further described The auxiliary g5 ergy has been so stored, and also during all such functions, ow ve S as Swinging and thrusttimes as the direct demands upon the prime movin the pp e f e ed th oug an auxiliary or are heavy; and for automatically resuming the hydraulic y pr y Such as will storage of energy whenever neither of these conbe sc i dditions exists. The hydraulic system includes a high pressure 30 Since myinventlon thus to a large extent evens reservoir to h b om of which liquid is off peak loads, it allows the use of smaller, and pp from a pu p (which m y be of y therefore less expensive prime movers. ppr priat d s a thcreforc e not be In addition to the objects stated above, I have m e parti u arly des ri d), a a ns a resilient worked out anumber of novel and useful details, cushion of Compressed in t head end of the 35 which will be readily evident as the description reservoir. The pump is driven by the electric progresses. motor through shaft 28. It receivesliquld through My invention consists in the novel parts, and 8- p p a d discharges through p p m the combinations and arrangements thereof, p 91 connected t usha lay-pass d v 53, 40 which are defined in the appended claims; and hereinafter described, to the base of the reser 40 of which one embodiment is exemplified in the voir 24, in which the pump maintains a working accompanying drawings, which are herein-utter pressure. The by-pass device 53 automatically particularly described and explained. unloads the pump when the pressure in the high. Throughout the description, the same referpressure reservoir 24 reaches a predetermined ence number is applied to the same member or maximum, and also during all times when the to similar members. direct demand on the prime mover exceeds a pre- Referring to the drawings. it will he seen that: determined amount; and automatically resumes Figure 1 is a fragmentary plan view of a power the storage of energy whenever neither of these shovel equipped with a hydraulic drive system conditions exists.

5o embodying the present invention, The pipe 28 leading to the pump is preferablyv 5a Figure 2 is a side elevation of certain elements supplied with liquid under low pressure from an shown in Figure 1. appropriate low pressure reservoir 30. Liquid Figure 3 is a somewhat diagrammatic repreis supplied to the bottom of the reservoir 30, sentation of the essential parts of my drive sysagainst an air cushion in the head end thereof, 55 tern, with the details oimy device for automatby a gear pump 3! or a well known type. The as pump 6| receives its supply from an appropriate supply reservoir 32 through a pipe 33 and discharges through a pipe 36 into the base of low pressure reservoir 30. A pressure relief valve,

conventionally indicated at 35 connected across the supply and discharge pipes 33 and 36, determines the pressure in pipe 96 and consequently in the reservoir 30. The gear pump 3| is driven through an appropriate belt and pulley connection 26 from the shaft 26; Valve controlled drain pipes 61 and 26 permit the contents of the high and low pressure reservoirs to be emptied into the supply tank when out of service.

In the hydraulic system shown, two variable torque hydraulic motors 39 and 39 are employed for driving the swing mechanism and the dipper thrust or crowding mechanism, respectively. Both are of the type described in.my copending Patent No. 1,793,438, issued February 17, 1931.

They are driven by liquid supplied from the.

high pressure reservoir through a manifold 60 and branch pipes 6i and 6|, respectively, and the liquid discharged by them is directed into the low pressure reservoir through branch pipes 62 and 62', respectively, and manifold 66. An appropriate cut-oft valve 66 is preferably provided in each manifold 66 and 63 to be closed when the shovel is not in use. The operation of each motor is regulated and controlled by a rock shaft 65, 65', through which the displacement, and consequently the torque, of each motor is varied in a manner described in said first mentioned application. Rock shaft 65 is actuated and controlled by an appropriate hand lever 66 fixed thereto, and rock shaft 65' is placed under the control of a hand lever 66' loosely mounted on shaft 65 and connected to shaft 65' through appropriate linkage 61. I

The motor 69 drives the shalt i5 through a conventional bevel gears 66 and 69 and a pair of spur gears 56 and 5| to swing the platform II in either direction under the control of lever 66; and motor 66' drives the usual shipper shaft (not shown) through appropriate means such as a sprocket and chain connection 62 to thrust or retract the dipper under the control of the lever 66.

From the foregoing it will be noted that in the drive system shown the hoist drum I1 is directis driven from the prime mover 20, sothat practlcally the entire power output thereof is available for peak hoisting loads. The average power consumption of the hoist mechanism however is considerably less than the maximum power capacity of the prime mover, the diilerence being more than suiiicient to supply the combined average power demands of the swing and thrust mechlnisms. In this instance the high pressure reservoir 26 serves as a power storage'medium, to which power is supplied through the pump 25 from the prime mover, and by which energy from the prime mover in excess of the demands of the hoist mechanism. is rendered available to operate the swing and thrust mechanisms.

Figure 8 is intended to show in detail the construction of the by-pass device, 53, for unloading the pump 25,. as previously explained, and to show the various connections thereto. For this reason some of the other instrumentaiities have been conventionalized or omitted in the interest of clearness. Thus, in Figure 3 the storage tank, shown as 92 in Figures 1 and 2, the gear pump II and its connections, and the motor 39 and itsgoverning devices, have been omitted.

In this figure, the electric motor 26 is shown gear train comprising a pair of.

as driving the pump 25 through shaft 26. From low pressure tank 30, pipe 28 conveys liquid to the pump. Pipe 29 conveys the liquid to the by-pass device 53. This device has several annular chambars, 56, 55, 56, through the center of which slides a shiftable valve member, 51, said valve member being cut away at'its central portion 56, as shown, so as to be capable of connecting annular space 55' with either one .of the annular spaces 56 or 56. Thus, with the valve member in position'as shown in Figure 3, there is free communication between annular chambers 56 and 55, by way of the space surrounding the cut away portion 56 of the valve member 51.

Separated from the three annular spaces 56, 55, 56, and more or less surrounding them, the by-pass device 53 contains a larger space 59, which communicates directly, by pipe 60, with low pressure tank 30.

One end of shiftable valve member 51, consists of a stem 6|, working in a chamber 62, and surrounding by a helical compression spring 63. One end of this spring bears against the shiftable valve member 51, and the other end bears against an adjusting plate 66, carried as shown by a screw threaded into the end of the by-pass device 56. The spring 66 therefore exercises an adjustable thrust upon the valve member 51,

tending to close annular chamber 56 and to maintain free communication between chambers 56 and 55. Chamber 62 communicates freely with chamber 59.

The other end of valve member 51 carries a portion 65. which operates as a piston in a cylindrical chamber 66. At their contiguous ends, chambers 66 and 59 communicate freely.

From high pressure tank 26 a pipe 61 conveys liquid under pressure to pressure regulator 56. This regulator contains a valve 69 which is opened by excess pressure in tank 26 against the pressure of a helical spring 16. The tension in spring 16, and therefore the'pressure necessary toopen valve 69, are adjustable, as shown, by the adjusting screw 1i. A pipe 12 connects the pressure regulator 66, as shown, with the cylindrical chamber containing piston'65.

When settings of all portions of my device are as shown in Figure 3, and motor 26 is driving pump 25, through shaft 26, liquid v will be pumped from low pressure tan 20, passing by pipe 26 to pump 25, and thence by pipe 29 tothe chamber 55. Communication between chambers 55 and 56 being open, liquid under pressure will pass, by pipe 12, to high pressure ,tank 26. If valve 66 is open, liquid under pressure actuates variable torque motor 39, and is returned'to the low pressure tank 66 by way of pipe 66.

Adjusting screw 1|, in the head of pressure regulator valve 69 seated against any pressure less than a certain predetermined maximum. When the pressure in tank 26 exceeds this maximum, it is communicated by pipe 61, to valve 69, which it raises from its seat. Liquid under pressure then flows by pipe 12 to the head of piston 65, forces the piston against the pressure of spring 56, thereby closing the ports into annular space 56, and opening communication between annular spaces and 56. Liquid delivered by pipe 29 into annular space way of space 56 and pipe 12 into the high pressure tank 26, but must pass into annular space 56, and back to low pressure tank 36 by way of pipe 13. During such times, therefore, that the pressure in high pressure tank 26 is at the de- 66, is supposed to be adjusted to keep,

55 now no longer flows by I sired maximum, the pump 23 is merely driving liquid from the low pressure tank, through a negligible amount of friction, hack to the low pressure tank. It is therefore practically idling, leaving the full power of the motor 20 available for the instrumentality directly driven by the motor.

When, by reason of the actuation of motor 39 by the pressure in tank 2i, that pressure has again become reduced below that for which the pressure regulator 68 is set, valve 69 will then close. A small tube N is provided in the casting which serves as cylinder for the piston 55, to allow the liquid to pass at a relatively slow rate from the high pressure side of piston 85 to the low pressure side 66.. Spring 63 then restores the valve member 51 to the position shown in Figure 3, and pressure is again built up in tank 24.

But it may be desirable, or even compulsory, to use the full power of the motor 2B for the directly driven instrumentality-in this case, the hoist drum i'l, shown in Figure l-at times when tank 24 is not up to full pressure, and when valve 69, in the pressure regulator 63, is therefore closed. In order to relieve the motor in such a case, I have added the device now to be described.

Projecting an appreciable distance through the casing of the by-pass valve 53, and integral with the piston end of the shiftable valve member 5! and axial thereto, is a rod 15. Abutting the end of this rod is a rod 16, which iscarried by the magnetizable core 11 of a solenoid 1B. The solenoid is connected by wires 19, through an overcurrent relay (not shown) to the source that supplies power to the motor.

mands upon the motor exceed the predeter- 'mined amount for which the overcurrent relay is set, the relay connects the solenoid to the power line, and the core 11, being drawn into the solenoid, thrusts against the rod 15, thereby to l ' anisin; a hydraulic pressure reservoir; a constant communication between spaces closing the ports oi annular space 56, opening 55 and 58, and relieving the motor of the task of driving the pump. When the power demand on the motor falls below the predetermined amount, the over current relay cuts out the solenoid, and spring 53 restores the valve member to the position in which the storage of energy is again resumed.

Having now described and illustrated one form of my invention, I wish it to be understoodthat my invention is not to be limited to the specific form or arrangement of parts hereinbefore described, except in so far as such limitations are specified in the appended claims,

I claim: 1. In a power excavator, the combination of a prime-mover; hoist mechanism, directly driven by said prime-mover; auxiliary excavating mechdisplacement hydraulic pump, driven by the prime-mover, and feeding the reservoir; an unloading valve, actuable to completely unload the pump; means, adapted to move in. one direction responsive to overload on the prime-mover, and

- adapted to move in the opposite direction when overload ceases; means cperably connecting the last named means to the unloading valve; means, adapted to move in one direction responsive to a pressure above a certain predetermined figure in the reservoir, and adapted to move in.

the opposite direction when the pressure falls below that figure; means operably connecting the last named means to the unloading valve; and a controllable hydraulic motor, fed by the reservoir, and-driving the auxiliary excavating mechanism,

2. In a power excavator, the combination or z a prime-mover; hoist mechanism, directly driven by said prime-mover; auxiliary exc vati mechanism; a hydraulic pressure reservoir; a constant displacement hydraulic pump, driven by the prime-mover, and feeding the reservoir; an tillloading valve, actuable to completely unload the pump; means, adapted to move in one direction responsive to a pressure above a certain predetermined figure in the reservoir, and adapted to move in the opposite direction when the pressure falls below that figure; means operably connect ing the last named means to the unloading valve; and a controllable hydraulic motor, fed by the reservoir, and driving the auxiliary excavating mechanism.

3. In a power excavator, the combination of: a prime-mover; hoist mechanism, directly driven by said prime-mover; auxiliary excavating mechanism; a hydraulic pressure reservoir; a constant displacement hydraulic pump, driven by the prime-mover, and feeding the reservoir; an um loading valve, actuable to completely unload the pump; means, adapted to move in one direction responsive to overload on the prime-mover, and adapted to move in the opposite direction when the overload ceases; means operably connecting the last named means to the unloading valve; and a controllable hydraulic motor, ied by the resei vcir, and driving the auxiliary excavating mechanism.

4. In a power excavator, the combination of: a prime -mover by said prime-mover; auxiliary excavating mechanism; a hydraulic low-pressure reservoir; a hydraulic high-pressure reservoir; a constant displacement hydraulic pump, driven by theprirnemover, drawing from the low-pressure reservoir, and feeding the high-pressure reservoir; a by pass valve, actuable to divert the pump so that it will feed back into the low-pressure reservoir; means, adapted to move in one direction responsive to overload on the prime-mover, and adapted to move in the opposite direction when the cver load ceases; means operably connecting the last named means to the bypass valve; means, adapted to move in one direction responsive to a pressure above a certain predetermined figure in the reservoir, and adapted to move in the opposite direction when the pressure falls below that he'- ure; means cperably connecting the last named means to the lay-pass valve; and a controllable hydraulic motor, fed by the high-pressure reservoir, and driving the auxiliary excavating meehii. In a. power excavator, the combination of: a primamover; hoist mechanism, directly driven by said prime-mover; auxiliary excavating mechanism; a hydraulic pressure reservoir; a con-- stant displacement hydraulic pump, driven by the primemiover, and feeding the reservoir; mechanism actuable to unload the pump; mech anism directly responsive to the load on as distingu shed from the speed of) the prime mover; an operative connection whereby the last named mechanism actuates the first; mechanism re sponsive to the pressure in the reservoir; an op erative connection whereby the lat named mechaniszn actuates the first; and a controllable lay: draulic motor, fed bythe reservoir, and driving the auxiliary excavating mechanism.

6. In a power excavator, the combination of: a

primeinover; hoist mechanism, directly driven hoist mechanism directly driven iii by said prime-mover; auxiliary excavating mechanism; a hydraulic pressure reservoir; a constant displacement hydraulic pump, driven by the prime-mover, and feeding the reservoir; mechanism actuable to unload the pump mechanism directly responsive to the load on guished from the speed of)- the prime-mover; an operative connection whereby the last named mechanism actuates the flrst; and a controllable hydraulic motor, fed by the reservoir, and driving the auxiliary excavating mechanism.

7. In a power shovel, a frame, a boom, a dipper thereon including a reciprocably movable handle and thrust mechanism therefor, a cable drum on said frame having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system comprising a pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for said thrust mechanism between said high and low pressure lines, a by-pass line between said latter lines, a pressure tank connected to said high pressure line, and means responsive to a predetermined pressure in said tank for opening said by-pass line to cause the pump to pump back into the low pressure line, with the pressure on both sides of the pump practically equalized.

8. In a power shovel, a base, a swinging platform thereon, mechanism for swinging said platform relative to said base, a boom on said plat form supporting an excavator, a cable drum on said platform having flexible cable connections on said excavator, a constant speed engine on said platform having optional driving connections with said cable drum, a hydraulic pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for said swing mechanism between said high and low pressure lines, a by-pass line between said latter lines, a'pressure tank connected to said high pressure line, and means responsive to a predetermined pressure in said tank for opening said by-pass line to cause the pump to pump back into the low pressure line, with the'pressure on both sides of the pump practically equalized.

9. In a power shovel, a frame, a boom, a dipper, auxiliary excavating instrumentalitics, a cable drum on said frame having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system including a pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for one of said auxiliary excavating instrumentalities between said high and low pressure lines, a pressure tank connected to said high pressure line, and means responsive to a predetermined pressure in said tank to cause the pump to pump back into the low pressure line, with the pressure on both sides of the pump practically equalized.

10. In a machine of the character described, a prime-mover, a hoisting winch having optional direct driving connection with the prime-mover, a hydraulic pump driven by said prime-mover, a highpressure line, a low pressure line, hydraulic power devices connected between said high and low pressure lines, a by-pass line connected between said high and low pressure lines and having a pressure responsive valve therein characterized I by being operable to wholly unload the pump by causing it to pump directly back into the low pressure line against merely the pressure in the low pressure line, a pressure tank connected to (as distine,

said high pressure line, and a pipe leading from said tank to said pressure-responsive valve and supplying pressure to open the latter when the pressure in said tank exceeds a predetermined value.

11. In a power excavator, the combination of: a prime-mover; hoist mechanism, directly driven .by said prime-mover; auxiliary excavating mechanism; a hydraulic pressure reservoir; a constant displacement hydraulic pump, driven by the prime-mover, and feeding the reservoir; an unloading valve, actuable to completely unload the pump; means biasing this valve to remain in or return to its non-unloading position; a hydraulic piston, so operatively associated with the unloading valve, as to move the unloading valve to unloading position, when actuated; a pressure responsive valve, adapted to admit hydraulic fluid from the reservoir to the piston, whenever the pressure in the reservoir exceeds a predetermined maximum; a solenoid, so operatively associated with the unloading valv'e as to move the unloading valve to unloading position, when actuated: means to actuate the solenoid whenever the load on the prime-mover exceeds a predetermined maximum; and a controllable hydraulic motor, fed by the reservoir, and driving the auxiliary excavating mechanism.

12. In a power shovel, a frame, a boom, a dipper, auxiliary excavating instrumentalities, a cable drum on said frame having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system including a pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for one of said auxiliary excavating instrumentalities between said high and low pressure lines, a pressure tank connected to said high pressure line, and means responsive to a predetermined pressure in said tank to shut off said tank from both the low pressure line and the outlet of the pump, and at the same time connect the outlet of the pump to the low pressure line.

13. In a power'shovel, a frame, a boom, a dipper. auxiliary excavating instrumentalities, a cable drum .on said frame having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system including a pump driven by said engine,

follows: the valve has two positions, namely- (1) the outlet of the pump is connected to the entire high pressure line, and the low pressure line is shut off from both; and (2) the high pres-. sure line is blocked between the pump and the tank, and that part of r the high pressure line between the pump and the valve is connected to the low pressure line, position No. 1 being the normal position; means responsive to tank-pressure above a predetermined maximum to cause the valve to assume position No. 2; and means to restore the valve to position Noel when the pressure drops below this maximum.

14. In a power shovel, a frame, a boom, a dipper, auxiliary excavating instrumentalities, a cable drum on said frame having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system including a pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for one of said auxiliary excavating instrumentalities between said high and low pressure lines, a pressure tank connected to said high pressure line, a valve characterized as follows: the valve has two positions, namely (.1) the outlet of the pump is connected to the entire high pressure line, and the low pressure line is shut off from both; and (Z) the high pressure line is blocked between the pump and the tank, and that part of the high pressure line between the pump and the valve is connected to the low pressure line, position No. 1 being the normal position; means responsive to tank-pressure above a predetermined maximum to cause the valve to assume position No. 2; means responsive to load on the engine above a predetermined maximum to cause the valve to assume position No. 2; and means to restore the valve to position No. 1 when both the pressure and the w load drop below their respective maxima.

WALTER FERRIS. 

